共查询到20条相似文献,搜索用时 322 毫秒
1.
Mohammad Reza Hajiaboli 《International Journal of Computer Vision》2011,92(2):177-191
Fourth-order nonlinear diffusion filters used for image noise removal are mainly isotropic filters. It means that the spatially
varying diffusivity determined by a diffusion function is applied on the image regardless of the orientation of its local
features. However, the optimal choice of parameters in the numerical solver of these filters for having a minimal distortion
of the image features results in forming speckle noise on the denoised image and a very slow convergence rate especially when
the noise level is moderately high. In this paper, a new fourth-order nonlinear diffusion filter is introduced, which has
an anisotropic behavior on the image features. In the proposed filter, it is shown that a suitable choice for a set of diffusivity
functions to unevenly control the strength of the diffusion on the directions of the level set and gradient leads to a good
edge preservation capability compared to the other diffusion or regularization filters. The comparison of the results obtained
by the proposed filter with those of the other second and fourth-order filters shows that the proposed method produces a noticeable
improvement in the quality of denoised images evaluated subjectively and quantitatively. 相似文献
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This paper provides a robust scheme for random valued impulsive noise reduction along with edge preservation by anisotropic diffusion with improved diffusivity. The defective impulse noisy pixels are detected by Laplacian based second order pixel difference operation where these defective pixels are replaced by appropriate values with regard of the gray level of their four directional neighbors. This de-noised image undergoes the diffusion operation where diffusion coefficient function is modified to make it adaptive by incorporating local gray level variance information. The proposed modified diffusion scheme effectively restore the edges and fine details destroyed during impulse noise reduction process. The effect of proposed diffusion scheme has been studied on various images and the results are compared with some existing diffusion methods which are independently used for impulse noise reduction and edge preservation. The results shows that the prior removal of impulsive noise before the application of diffusion process is advantageous over the direct application of diffusion for removing the impulsive noise. In addition, the results of the proposed diffusion scheme are compared with some of the median filter based methods which are effectively used for impulse noise reduction without caring of edge preservation. The proposed diffusion scheme sufficiently preserves the edges without boosting of impulsive noise components on images corrupted up to 50 % of the impulsive noise density. 相似文献
4.
正电子发射断层重建是一类不适定问题,因此正则化方法常用来抑制噪声提高重建的质量.依据Mumford-Shah泛函模型提出了该类重建问题的统一变分模型.基于这一模型,提出了一种新的基于扩散方程的PET重建算法,同时给出了线性和非线性两种方法.实验结果表明,两种方法均有良好的重建性能,并且非线性方法通过合理的设置参数,能体现出较为优越的抗噪声性能和边缘保持特性. 相似文献
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PDE模型在声纳图像去噪中的应用研究 总被引:1,自引:0,他引:1
偏微分方程方法在光学图像去噪中已有很多成功的应用,但用于声纳图像去噪的情况还不多见。针对声纳图像受噪声污染严重的问题,将偏微分方程原理引入到声纳图像去噪中,重点讨论了两种偏微分方程模型:ROF模型和四阶扩散模型。基于这两种模型对声纳图像进行去噪处理,仿真实验证明了偏微分方程去噪算法的有效性,并对比分析了两种模型的去噪性能。ROF模型适用于低信噪比条件下的声纳图像处理,而四阶扩散模型在高信噪比条件下,能够很好地保持图像边缘,但当噪声污染严重时,其去噪后的SNR比ROF模型去噪低了近10 dB,不利于声纳图像处理。 相似文献
7.
Ayyaz Hussain Sohail Masood Bhatti M. Arfan Jaffar 《Multimedia Tools and Applications》2012,60(3):551-571
In this paper, we propose an image filtering technique based on fuzzy logic control to remove impulse noise for low as well as highly corrupted images. The proposed method is based on noise detection, noise removal and edge preservation modules. The main advantage of the proposed technique over the other filtering techniques is its superior noise removal as well as detail preserving capability. Based on the criteria of peak-signal-to-noise-ratio (PSNR), mean square error (MSE), structural similarity index measure (SSIM) and subjective evaluation measure we have found experimentally that the proposed method provides much better performance than the state-of-the-art filters. To analyze the detail preservation capability of the proposed filter sensitivity analysis is performed by changing the detail preservation module to see its effects on the details (texture and edge information) of resultant image. This sensitivity analysis proves experimentally that significant image details have been preserved by the proposed method. 相似文献
8.
针对传统各向异性扩散方法在超声图像散斑噪声抑制中存在的噪声抑制不充分与边缘特征保持不足的问题,提出一种基于Mallat-Zhong离散小波变换(MZ-DWT)小波的散斑噪声抑制方法。该方法将MZ-DWT小波分析与期望值最大化(EM)算法作为图像中均匀区域与边缘区域的鉴别因子,使扩散系数能够更准确地控制扩散强度与扩散速度,从而达到充分抑制噪声和保护边缘的目的。实验结果表明,所提方法在有效抑制散斑噪声的同时,更好地保持了图像细节信息,其性能优于传统各向异性扩散方法。 相似文献
9.
Anisotropic partial differential equations (PDEs) based schemes for denoising digital images are fast becoming an indispensable tool in computer vision problems. In this paper we propose to denoise noisy images via such multiscale anisotropic diffusion. In general, digital images contain objects of multiple scales and denoising them without destroying edges is one of the main objective in early computer vision problems. Unlike the previous approaches, which discard the multiple scale based images produced by anisotropic PDE, we utilize information contained in them. By effectively combining the inter-scale details, the proposed scheme improves upon the noise removal and detail preservation properties over other schemes. Numerical results indicate that the scheme achieves good denoising with edge preservation on a variety of images. 相似文献
10.
Jinhua Yu Author Vitae Author Vitae Yuanyuan Wang Author Vitae 《Pattern recognition》2010,43(9):3083-3092
An ultrasound speckle reduction method is proposed in this paper. The filter, which enhances the power of anisotropic diffusion with the Smallest Univalue Segment Assimilating Nucleus (SUSAN) edge detector, is referred to as the SUSAN-controlled anisotropic diffusion (SUSAN_AD). The SUSAN edge detector finds image features by using local information from a pseudo-global perspective. Thanks to the noise insensitivity and structure preservation properties of SUSAN, a better control can be provided to the subsequent diffusion process. To enhance the adaptability of the SUSAN_AD, the parameters of the SUSAN edge detector are calculated based on the statistics of a fully formed speckle (FFS) region. Different FFS estimation schemes are proposed for envelope-detected speckle images and log-compressed ultrasonic images. Adaptive diffusion threshold estimation and automatic diffusion termination criterion are employed to enhance the robustness of the method. Both synthetic and real ultrasound images are used to evaluate the proposed method. The performance of the SUSAN_AD is compared with four other existing speckle reduction methods. It is shown that the proposed method is superior to other methods in both noise reduction and detail preservation. 相似文献
11.
针对各向同性扩散易于造成图像边缘等特征区域的模糊以及相干增强扩散易于在图像背景区域内产生伪条纹的问题,提出了一种根据磁共振成像(MRI)图像莱斯噪声分布特点来对其进行降噪的加权扩散算法。该算法以MRI图像背景区域的莱斯噪声方差作为区分MRI图像背景区域和感兴趣的边缘特征区域二者特征差异的阈值。基于该阈值,该算法构造了一个加权函数,并用该函数对各向同性扩散和相干增强扩散进行加权。加权函数根据图像在不同结构区域的变化,自适应地调整两种扩散的权值,从而充分发挥两种扩散的优势并克服各自的不足。实验结果表明,该算法在峰值信噪比(PSNR)及平均结构相似度(MSSIM)的评价上优于一些经典算法。因此,该算法的降噪及保护、增强边缘的能力更为优越。 相似文献
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为了在消除噪声的同时保留或加强图像中的细节,提出了一种模糊边缘敏感去噪算法.该算法在有关人类视觉系统特性的基础上,结合模糊逻辑技术,判断像素所处的位置,并采用相应的滤波策略以进行噪声消除.实验结果表明,该算法在高斯噪声平滑、脉冲噪声消除以及边缘保留方面,相比其他一些算法,如传统的边缘敏感噪声消除算法以及模糊去噪算法,能提供更好的性能. 相似文献
13.
二阶偏微分方程图像去噪方法在去除噪声同时保护边缘效果较好,但在平滑区会产生阶梯效应,而四阶方法可以消除阶梯效应,基于此提出了一种将二阶与四阶偏微分方程相结合的变分去噪方法,给出了其欧拉方程和梯度下降流,并分析了数值离散化方法。通过去噪实验表明,该方法能有效去除噪声干扰,在一定程度上保护边缘,并且可以有效减弱阶梯效应,改善图像质量。 相似文献
14.
针对传统的各向异性扩散去噪方法存在的导致图像细节丢失的问题,提出了一种基于平稳小波域的各向异性扩散图像去噪方法。该方法根据平稳小波变换的特性,通过在高频和低频子带上选用不同的梯度门限进行各向异性扩散,然后进行重构得到去噪后的结果图像。实验结果表明,该方法在有效去除噪声的同时,图像细节保留较好,去噪后的图像具有更好的质量。 相似文献
15.
Iterative Image Restoration Combining Total Variation Minimization and a Second-Order Functional 总被引:9,自引:0,他引:9
A noise removal technique using partial differential equations (PDEs) is proposed here. It combines the Total Variational
(TV) filter with a fourth-order PDE filter. The combined technique is able to preserve edges and at the same time avoid the
staircase effect in smooth regions. A weighting function is used in an iterative way to combine the solutions of the TV-filter
and the fourth-order filter. Numerical experiments confirm that the new method is able to use less restrictive time step than
the fourth-order filter. Numerical examples using images with objects consisting of edge, flat and intermediate regions illustrate
advantages of the proposed model.
This work has been supported by the Research Council of Norway. 相似文献
16.
提出一种医学图像解剖结构特征提取算法,结合异质扩散和小波包分解实现了医学图像分割.在异质扩散基础上,提出一种新的FAB扩散方法对图像进行去噪,同时保持图像解剖结构的边缘和局部细节;然后用一个基于小波包分解的自适应边缘检测算法来检测图像的解剖结构的轮廓特征.分割结果表明,该方法能在有效地去除噪声的基础上完成医学图像解剖结构轮廓特征的提取. 相似文献
17.
为了增强锅炉水位计图像滤波去噪效果,提高图像清晰度,便于后期液位计图像识别研究,通过分析P-M各向异性扩散模型、选择扩散模型及You Yu-Li和Kaveh M四阶偏微分方程的滤波去噪算法,提出了改进各向异性扩散模型滤波算法.所提算法对Perona和Malik两个扩散函数均值化,并引入标准差作为梯度期望值的偏差裕度,结合了P-M各向异性扩散模型保边缘特性的优点,并消除了由于传统各向异性滤波算法迭代过度所造成的阶梯缺陷问题,确保图像有用信息不缺失和像素点平滑度.实验结果表明:所提算法能够更好地降低噪声对目标信号提取产生的影响,提高了图像识别鲁棒性,增强了图像平滑滤波效果,保证了锅炉水位计图像边缘清晰度和完整性. 相似文献
18.
基于视觉掩蔽效应的图像扩散 总被引:1,自引:0,他引:1
提出一种基于视觉掩蔽效应的图像扩散算法.结合人类视觉系统的特性,利用图像上下文像素的非均质性度量定义了新的噪声掩蔽函数,可以有效地区分噪声和边缘特征,由此得到的噪声可见度函数作为各向异性扩散的扩散系数.算法同时利用了图像的局部梯度信息和较大邻域的上下文信息,可以在滤除噪声的同时更加有效地保留图像的重要特征,而且避免了传... 相似文献
19.
Jian Wu Chen Tang 《Pattern recognition letters》2011,32(15):1974-1981
In this paper, we propose an improved two-stage scheme for the removal of salt-and-pepper noise based on an efficient impulse detector and the edge-preserving total variation inpainting model. We test the proposed algorithm on the four images corrupted by salt-and-pepper noise with a wide range of noise levels varied from 10% to 95%, and compare it with the six other well known filters. Further, we evaluate quantitatively the performance of these filters with the peak signal-to-noise ratio (PSNR), the measure of structural similarity (SSIM) and the image enhancement factor (IEF). The experimental results have demonstrated that the proposed filter performs impressively in noise suppression and edge preservation. 相似文献